diff --git a/bit_manipulation/find_number_that_appears_only_once_in_array.py b/bit_manipulation/find_number_that_appears_only_once_in_array.py
new file mode 100644
index 000000000000..edb4aa92d2cc
--- /dev/null
+++ b/bit_manipulation/find_number_that_appears_only_once_in_array.py
@@ -0,0 +1,24 @@
+def find_single_number(nums: list[int]) -> int:
+    """
+    LeetCode 136: Single Number
+    https://leetcode.com/problems/single-number/
+
+    >>> find_single_number([1, 4, 1, 7, 9, 2, 9, 7, 2])
+    4
+    >>> find_single_number([1, 2, 4, 1, 4, 3, 2])
+    3
+    >>> find_single_number([4, 1, 2, 1, 2])
+    4
+    """
+    single_num = 0
+
+    for i in nums:
+        single_num = single_num ^ i
+
+    return single_num
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()